Suicide bombers wearing belts with explosives caused twin blasts that killed more than 30 people on Monday at two central Moscow metro stations, Moscow's chief prosecutor said.
"We can assume that belts with explosive devices were attached to their bodies," Yuri Syomin told reporters on Lubyanka square above the site of the first metro explosion.
"The scenario was similar at Park Kultury" metro station, where the second blast took place, he said.
At least 19 people were killed in the first explosion and 14 dead in the second, he said.
"These are not the definitive tolls yet, but at the moment it is time to concentrate on saving lives," Syomin added.